Ball-caster.



PATENTED APR. 14, 1903.

G. THOMSON.

BALL GASTER.

APPLICATION FILED JUNE 4, 1900.

N0 MODEL.

*f' {INVENTOR BY z ATTORNEY 3 UNITED STATES CLIFFORD THOMSON, OF EASTORANGE, NEYV JERSEY, ASSIGNOR TO THE ACME BALL BEARING OASTER COMPANY, ACORPORATION OF NEW JERSEY.

BALL-CASTER.

S PECIFIGATION forming part Of Letters Patent No. 725,174; dated. April14:, 1903. Application filed Tune 4, 1900. Serial No. 19,008. (Nomodel.)

To all whom it may concern:

Be it known that I, CLIFFORD THOMSON, a citizen of the United States,and a resident of East Orange, county of Essex, and State of New Jersey,have-invented certain new and useful Improvements in Ball-Oasters,ofwhich the following is a specification.

My invention relates to that class of ballcasters in which the largerbearing-ball supro ports its load through the intervention of a numberof relatively smaller antifrictionballs, and more particularly to thattype of such casters in which a ball-guiding reliefchamber is providedto receive the antifriction-balls as they leave the bearing-ball andguide them back to another point on the bearing-ball, where they areneeded to take active part in supporting the load carried by the casterand prevent friction. In constructing so casters of this special type ithas heretofore been considered necessary not only to make the distancebetween the walls of the ballguiding chamber materially greater than thediameter of the antifriction-balls, but also to make the said chamber ofconsiderable size and extend it to the rear of the member carrying thebearing-surface of the caster, so as to form a kind of a reservoir forthe antifriction-balls. This construction, although satisfactory inoperation, necessitates the use of alarge number ofantifriction-ballsand is otherwise expensive to manufacture.

My inventionhas for an object to provide, in a caster of the typereferred to, a ball-guiding relief-chamber of such form and dimensionsas to permit of the caster being constructed and operated with a muchsmaller number of antifriction-balls than is required in such casters asheretofore constructed.

Other objects of my invention are to do away with the necessity of aseparate bearing member and to otherwise improve and simplify andcheapen the construction of the type of caster referred to.

My invention'consists of the novel features of construction andcombinations of parts herein described.

The accompanying drawings, which are referred to herein and form a parthereof, illustrate, by way of example, one embodiment of my inventionand serve in connection with the following description to explain theprinciples thereof and the best mode in which I have contemplatedapplying those principles.

Of the drawings, in which like referencenumerals refer to like parts,Figure 1 is a vertical central section of the casing of. a casterconstructed in accordance with my invention, the bearing-ball and theantifrictionballs being shown in elevation. Fig. 2 is a side elevationof the caster, and Fig. 3 is a transverse section of the same in line AB of Fig. 1..

Referring to the drawings in detail, the easing of the caster isrepresented for convenience of construction as consisting of twoseparable parts 1 and 2, said parts being preferably secured together bymeans of corresponding screw-threads formed on their meeting ends, asshown. The casing of the caster is provided with suitable means by whichit may be attached to a piece of furniture or other object. In theexample shown this means comprises a pin 3, carried by the upper part 1of the casing. Within the casing thus formed a cavity is provided, inwhich the cooperative or functional parts of the caster are located.These parts consist of a larger bearing-ball 4., a plurality of smallerantifriction-balls 5, a concave bearing-surface 6, an annularball-guiding surface 7, and a ballguiding relief-chamber 8. As shown,the concave bearing-surface 6 is centrally located in the upper end ofthe cavity and is preferably formed directly on the lower end of theupper part 1 of the casing. The bearing-surface 6 should have acurvature such that when the ball 4 is separated therefrom by theantifriction-balls 5 or by a space equal to the diameter of saidantifriction-balls the bearing-surface and the bearing-ball will besubstantially concentric with each other. Thebearing-surface 6 ispreferably circular in outline, and it should be of such dimensions thatthere are always three at least of a diametrical line of the lowerend ofthe upper part 1 and an annular shoulder 10 of the lower part 2 of thecasing, as shown. The surface 7 is thus fixed with relation to both thebearing-surface and the bearing-ball and is so located as to guide theanti friction-balls 5 away from the surface of the bearing-ball 4 asthey pass from be tween the bearing-ball etand the bearing-surface 6, orvery soon thereafter. The surface 7 should be curved, so as to form acontinuous annular concaved surface, substantially as shown. The annularsurface 7 serves to guide the balls toward and into the chamber 8, whichis annular in form and is located adjacent to the bearing-surface 6,substantially as shown. The inner wallsof the chamber 8 are curved andshould form a continuation of the curved surface 7, and preferably thering 9 is of such form and dimensions that the surface 7 forms a portionof the walls of the chamber 8. The chamber 8 surrounds thebearing-surface 6 and preferably is concentric therewith and extendsabove the outer edge of the surface 6 when the caster is in an uprightposition, as shown. It is essential that the distance between theopposite walls of the chamber 8 should be materially greater in everydirection than the diameter of the antifriction-balls 5 and that theyhave a substantially unbroken curved conformation in order to preventthe binding of said balls when in action. On the other hand, while thereis no definite limit to the maximum size of the annular chamber 8, it isdesirable to make the space in said chamber as small as possible inorder that the caster may be constructed with the minimum numberofantifriction-balls. I have found that the easter may be made to operatesmoothly and without binding with a minimum number of antifriction ballswhen substantially the 7 whole of the ball-guiding relief-chamber islocated beyond the periphery of the bearingsurface and is madesubstantially elliptical or oblong in cross-section with the minor axisnot more than once and a half and the major axis not more than twice thediameter of the antifriction-balls. For the sake of economy in space andmaterials and for convenience of construction the relief-chamber ispreferably arranged with its major axis at substantially a right anglewith the general plane of the bearing-surface 6 and with the annularopening, through which the balls enter and leave the chamber, located atthe inner side of the portion thereof which is adjacent to the mainbearing-ball, substantially as shown. Any other form or arrangement ofthe annular chamber which may be suited to a particular form of castermay be adopted.

In operation the antifriction-balls 5 are guided away from the advancingside of the bearing-ball 4 by the guiding-surface 7 and into the chamber8, through which they are passed laterally in either direction by thevforce of the stream of balls issuing from between the bearing-ball andthe bearing-surface 6, and by the walls of which chamber theantifriction-balls are guided back to the opposite side of the caster,where they are needed to perpetuate the stream of balls forming theantifriction-bearing for the bearing-ball. Owing to the size of thechamber 8 and to the conformation of its walls the idle or returnantifriction-balls flow freely therethrough, and consequently anybinding of the balls when the caster is in operation is lessened orprevented. By reason of the annular form of the ball-guiding surfacesthe caster is free to move in any direction.

My invention is not limited to the particular construction shown anddescribed, nor to the particular construction by which it may be carriedinto effect, as many changes may be made therein without departing fromthe principles of my invention or sacrificing its chief advantages.

What I claim as new, and desire to secure by Letters Patent, is

1. A ball-caster comprising a casing having a cavity formed therein, abearing-ball held in cooperative relation with the casing, a concavebearing-surface located within said cavity and adjacent to thebearing-ball, an annular chamber formed in said cavity around and whollybeyond the periphery of the bearing-surface and adjacent to thebearing-ball, antifriction-balls located between the bearing-ball andthe bearing-surface and also in said chamber, the distance between thewalls of the said chamber and the conformation of said walls being suchas to form the returnball-guiding chamber of the caster, substantiallyas described.

2. A ball-caster comprising a casing having a cavity formed therein, abearing-ball held in cooperative relation with the casing, a concavebearing-surface located within said cavity and adjacent to thebearing-ball, an annular chamber formed in said cavity around and whollybeyond the periphery of the bearing-surface and adjacentto thebearing-ball, antifriction-balls located between the bearing-ball andthe bearing-surface, and also in said chamber, and means forming asuitable marginal guide for said antifriction-balls, the distancebetween the walls of the said chamher and the conformation of said wallsbeing such as to form the return-ball-guiding chamber of the caster andprevent binding of the balls when in operation, substantially asdescribed.

3. Aball-caster comprisinga casing having a cavity formed therein, abearing-ball in said cavity, a concave bearing-surface located withinsaid cavity and adjacent to the bearing-ball, an annular chamber formedin said cavity around the bearing-surface and adjacent to thebearing-ball, antifriction-balls located between the bearingball and thebearing-surface, and also in said chamber, substantially the whole ofsaid annular chamber being located beyond the periphery. of thebearing-surface and the distance between ICC the walls of said chamberbeing materially greater than the diameter of the antifrictionballs,whereby the caster may be operated with a minimum number ofantifriction-balls, substantially as described.

4. A ball-caster comprising a casing having a cavity formed therein,abearing-ball in said cavity, a concave bearing surface located withinsaid cavity and adjacent to the bearing-ball, an annular chamber formedin said cavity around the bearing-surface and adjacent to thebearing-ball, antifriction-balls located between the bearing-ball andthe bearing-surface and also in said chamber, and a ring formingasuitable marginal guide forsaid antifriction-balls, substantially thewhole of said annular chamber being located beyond the periphery of thebearing-surface and the distance between the walls of said chamber beingmaterially greater than the diameter of the antifriction-balls wherebythe caster may be operated with a minimum numberof antifriction-balls,substantially as described.

5. A ball-caster comprising a casing having a cavity formed therein, abearing-ball held in cooperative relation with the casing, a concavebearing-surface formed directly on the inner walls of said casingadjacent to the bearing-ball, an annular chamber formed in said cavityaround and wholly beyond the periphery of the bearing-surface andadjacent to the bearing-ball, and antifriction-balls located between thebearing-ball and the bearing-surface and also in said chamber, thedistance between the walls of the said chamber and the conformation ofsaid walls being such as to form the return-ball-guiding chamber of thecaster, substantially as described.

6. A ball-caster comprising a casing having a cavity formed therein, abearing-ball held in codperative relation with the casing, a concavebearing-surface located within said cavity and adjacent to thebearing-ball, an annular chamber formed in said cavity around and whollybeyond the bearing-surface and adjacent to the bearing-ball, andantifrictionballs located in said chamber and between the bearing-balland the bearing-surface, said chamber being substantially oblong insection and having a space between its walls materially greater than thediameter of the antifriction-balls, whereby binding of the balls when inoperation is prevented, substantially as described.

7. A ball-caster comprising a two-part casing, one part of which hasformed thereon a central concave bearing-surface and an annular concaverecess, a bearing-ball located in the other part of said casing, a ringhaving an inner concave surface located between the parts of the casing,said annular recess and said ring forming between them an annularchamber, and antifriction-balls located between the bearing-ball and thebearingsurface and also in said annular chamber the distance between thewalls of said chamber and the conformation of the said walls being suchas to form arelief-chamberand prevent binding of the balls when inoperation, substantially as described.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

CLIFFORD THOMSON.

